import java.util.Scanner;

public class ATMHomework {
    public static void main(String[] args) {
        Scanner scn = new Scanner(System.in);
        double banlance = 0;

        while(true){
            System.out.println("======ATM======");
            System.out.println("1.存款");
            System.out.println("2.取款");
            System.out.println("3.显示余额");
            System.out.println("4.退出");
            System.out.println("请选择（1-4）：");

            int res = scn.nextInt();
            System.out.println("你选择的是----》" +res);

            if(res==1){
                System.out.println("请输入存款金额");
                double price =scn.nextDouble();
                banlance = banlance + price;
                if( banlance  < 0){
                    System.out.println("存款金额不合法");
                }
            }

            else if(res==2){
                System.out.println("请输入取款金额");
                double price2 =scn.nextDouble();
                banlance = banlance - price2;

                if (price2 > banlance){
                    System.out.println("当前余额为：" +banlance +">余额不足");

                }else if(price2 < 0){
                    System.out.println("取款金额不合法");
                }else {
                    banlance = banlance - price2;
                }
            }

            else if(res==3){
                System.out.println("当前余额为：" + banlance);
            }

            else if(res==4){

                break;
            }

        }
    }
}
